Cone 06 - Mayco Dry Mix Glaze

[Maj0rMalfunct10n]

Hi,

 

I fired my kiln yesterday and I received some mixed results.

 

I follow a fairly strict process when firing my kiln (usually takes 8 or so hours) and have had good success in the past.  I don't mix my own glazes yet, and use dry mix from Mayco.

 

In this fire i received a fair amount of bubbles in the glaze.  I have attached a few photos.  I was wondering if this is a symptom of overfiring?  I am sure this is ceramics 101 but any input would be great.

 

thanks

 

~Mal

 

 

[pautts]

If I had to guess, I would say it is actually underfired. It looks like gases were trying to escape, but the glaze was too viscous to allow it to leave.

 

Are you firing with cones? some more info about your clay body, glaze, and firing schedule might help to point to a more definite cause.

[Maj0rMalfunct10n]

Hi pautts,

 

I do use cones, one in the kiln setter and one that I can view through the the plug hole. I have a couple of clay bodies in this instance both from Plainsman.

 

I turn the kiln on min for an hour with the lid notched open and He plugs out. I increase the temperature by moving the dials to one, then two and three each hour. Then I move to 3.5, 4 and then 4.5 each following hour. At 4.5 I close the lids do wait another hour when I put the plugs in and move the dial to 5. One more hour I move to 5.5. In this instance the kiln turned itself off shortly after. Aprox. 8 or so hours to fire. I have kept the cone from the stand and could photograph it if helpful. The cone in the kiln sitter was a complete "u" shape and triggered the kiln to trip off.

 

I keep a journal each time I fire and could provide exact times when the kiln was turned up.

 

I live in Canada and while there is no snow right now the day of the fire it did drop to 0 c or 32 f outside and I fire in a non heated garage. I normally don't fire this late in the season.

 

I did use one different glaze which is a dry mix Mayco glaze. All the glazes I use are store purchased, I only mix my own Raku glaze.

 

I can go into greater detail on any area. Any input is appreciated. Thanks.

 

~Mal

[neilestrick]

It looks like you're overlapping two different glazes? Have you use that combination before? Not all glazes play nice together. Also, when using dry mix, if you don't mix the entire batch with water all at once, you want to make sure you mix the powder well before using it. Sometimes heavier particles can settle to the bottom of the package, so when you make your glaze you're not getting the actual recipe in the mix.